1. Field of the Invention
The present invention relates to a recording medium for sublimation type heat-sensitive transfer recording process which forms a recorded image which has superior resistance to fading when exposed to light.
2. Background Art
Sublimation type heat-sensitive transfer recording process are advantageous in that the level of noise produced during recording is low, the apparatus used therefor is small and inexpensive, the maintenance thereof is easy, and the output time is short. Furthermore, since sublimation type dyes are used, by continuously varying the amount of the exothermic energy, high contrast recording may be easily achieved, and such recording exhibits high density and high resolution. As a result, in comparison with other recording methods, such a method is advantageous, especially for producing full color hard copy, and has been adopted as a recording method for color printers, video printers, and the like.
However, as the image recorded by means of such a sublimation type heat-sensitive transfer recording process is formed by means of sublimable dyes, the light resistance thereof is generally poor, and this is disadvantageous in that fade out and discoloration resulting from sunlight or fluorescent light exposure occurs easily. In order to solve this problem, an ultraviolet absorber or a photostabilizer was generally applied to the image receiving layer of the recording medium, and as a result of this, light resistance was somewhat improved; however, this improvement could not be termed sufficient. In addition, methods have been disclosed, such as that in Japanese Laid-Open Patent Application No. Hei 1-127387, in which a specified phenol antioxidant was applied to the image receiving layer, and that of Japanese Laid-Open Patent Application No. Hei 3-19893, and Japanese Laid-Open Patent Application No. Sho 61-229594, in which a specified phosphorus antioxidant was applied to the image receiving layer, and as a result of using these methods, a small increase in light resistance was observed; however, the degree of fade out and discoloration as a result of exposure to light was still large.